Optimization of the Decoking Procedure of an Ethane Cracker with a Steam/Air Mixture

Abstract

Using a heterogeneous plug flow model for the reactor tubes and a general gas−solid reaction/diffusion model with intrinsic reaction kinetics for coke combustion and coke gasification, an in-depth study on the influence of seven operating parameters of the decoking procedure of an ethane cracking furnace is performed. On the basis of the results of this study, the air and steam flow to the reactor tubes during the decoking procedure are adapted to propose an optimized decoking procedure that allows reducing the required decoking time of an industrial ethane cracking furnace by a factor of 3. In the new decoking conditions for the ethane cracker, the air flow rate is raised by a factor of 3, while the steam dilution is lowered by a factor of 4.5.

LiFePO4‐Accelerated Change in Surface and Electrochemical Properties in Aqueous Systems Induced by Mechanical Agitation

“…The oxidation of the amorphous carbon layer with water would seem unlikely, as the temperature for such processes, while used in commercial applications such as decoking of chemical reactor catalysts, typically must be very high (e.g., 1050 C). [48] The mechanical forces of the particles colliding with one another and the walls of the container could also damage the thin interfacial layer and carbon on the LFP, and this route would be consistent with the observed stir rate dependence of the rate at which the observed physical changes in the particles occur. Then, water would more easily access the previously unexposed LFP through the thinner or completely removed amorphous carbon layer (discussed further and with additional thermogravimetric analysis (TGA) on the material in Figure S11, Supporting Information).…”

“…It has previously been reported that water at higher temperatures (100 °C) can be used to remove amorphous carbon during the purification of carbon nanotubes, but the fundamentals of how water facilitates the removal of amorphous carbon are not well understood. The oxidation of the amorphous carbon layer with water would seem unlikely, as the temperature for such processes, while used in commercial applications such as decoking of chemical reactor catalysts, typically must be very high (e.g., 1050 °C) . The mechanical forces of the particles colliding with one another and the walls of the container could also damage the thin interfacial layer and carbon on the LFP, and this route would be consistent with the observed stir rate dependence of the rate at which the observed physical changes in the particles occur.…”

Thermal Cracking of Hydrocarbons for the Production of Light Olefins; A Review on Optimal Process Design, Operation, and Control

“…Apart from the mentioned works, which focused mostly on the optimization of operational parameters of cracking furnaces, limited efforts have been made to optimize the decoking process. , Heynderickx et al computed an optimal decoking procedure based on a detailed decoking model including reaction kinetics for coke combustion and coke gasification. Song and Tang, on the other hand, focused on the operation of the TLE system.…”

Catalytic Effect of Dimethyl Disulfide on Coke Formation on High-Temperature Alloys: Myth or Reality?

“…However, climate change makes it mandatory to replace fossil fuels with electricity, reactor materials will still be of high importance, in particular when moving a chemical industry that works based on Joule effect 4 . To avoid operation of the furnace above the metallurgical maximum allowable temperature or at the maximum pressure drop, an on-line decoking procedure of about 48 hours using steam, steam and hydrogen 5 or -more commonly -a steam/air mixture [6][7] is applied. The aim of decoking is to rapidly, safely and completely remove the coke formed on the coil, creating a continuous oxide layer at the interface of the gas and coil.…”